Interaction of phase singularities on the spiral wave tail: reconsideration of capturing the excitable gap

Abstract

The action mechanism of stimulation toward spiral waves (SWs) owing to the complex excitation patterns that occur just after point stimulation has not yet been experimentally clarified. This study sought to test our hypothesis that the effect of capturing excitable gap of SWs by stimulation can also be explained as the interaction of original phase singularity (PS) and PSs induced by the stimulation on the wave tail (WT) of the original SW. Phase variance analysis was used to quantitatively analyze the postshock PS trajectories. In a two-dimensional subepicardial layer of Langendorff-perfused rabbit hearts, optical mapping was used to record the excitation pattern during stimulation. After a SW was induced by S1-S2 shock, single biphasic point stimulation S3 was applied. In 70 of the S1-S2-S3 stimulation episodes applied on 6 hearts, the original PS was clearly observed just before the S3 point stimulation in 37 episodes. Pairwise PSs were newly induced by the S3 in 20 episodes. The original PS collided with the newly induced PSs in 16 episodes; otherwise, they did not interact with the original PS. SW shift occurred most efficiently when the S3 shock was applied at the relative refractory period, and PS shifted in the direction of the WT. In conclusion, quantitative tracking of PS clarified that stimulation in desirable conditions induces pairwise PSs on WT and that the collision of PSs causes SW shift along the WT. The results of this study indicate the importance of the interaction of shock-induced excitation with the WT for effective stimulation. NEW & NOTEWORTHY The quantitative analysis of spiral wave dynamics during stimulation clarified the action mechanism of capturing the excitable gap, i.e., the induction of pairwise phase singularities on the wave tail and spiral wave shift along the wave tail as a result of these interactions. The importance of the wave tail for effective stimulation was revealed.

Cardiac Spiral Wave Termination by Linear Regional Cooling Toward the Anatomical Boundary of the Heart

“…To discuss SW dynamics after conduction blockage, occurrence and annihilation dynamics of SWs should be considered. In a previous study about point stimulation during SW excitation, SW dynamics after conduction block were also discussed [35]. The study reported that conduction block generates two SWs, one clockwise and another counterclockwise.…”

Stop the beat to see the rhythm: excitation-contraction uncoupling in cardiac research

“…As shown in Figure 1, since its first use for optical mapping in 2007, blebbistatin has all but replaced the other available EC uncouplers. In fact, in the last three years alone, blebbistatin was used twice as often (1,29,36,41,51,56,59,69,74,76,78,83,85,87) as any other uncoupler for imaging applications (25,27,33,46,54,55,80). The use of BDM/DAM and CytoD for optical mapping has essentially ceased, yet due to its lower cost, BDM/DAM may still be a reasonable choice for larger animal (i.e., non-rodent) studies (10,23,25,35,52,70,77), which require larger amounts of an EC uncoupler (72).…”

Validation of Intraoperative Catheter Phase Mapping Using a Simultaneous Optical Measurement System in Rabbit Ventricular Myocardium

“…The details of the algorithm are described in other studies. [24][25][26] The phase value of each pixel in the camera image was calculated by applying reverse normalization and Hilbert transform to the OPT signal. using both mapping methods, and the activation pattern estimated by EXT was compared with that estimated by OPT.…”